Microelectronic devices include integrated circuits, flat panel displays, thin film heads, transistors, diodes, and the like. During manufacture, it is common for a plurality of microelectronic devices to be formed upon a thin slice of semiconductor material. This thin slice of semiconductor material is referred to as a semiconductor wafer. After the devices are formed on the wafer, the finished structure may be sliced into individual devices or clusters of such devices, as desired. Microelectronic devices, in-process microelectronic devices, and the wafers themselves tend to be brittle and extremely sensitive to contamination. Even minute traces of microscopic contaminants can significantly impair the performance of one or more of the devices being formed on a wafer. Thus, exceptional care is taken to clean, avoid damaging, and/or avoid contaminating in-process microelectronic devices.
To make microelectronic devices, in-process microelectronic devices generally are transferred to and from a succession of processing units. These units may be stand-alone stations all couple together in a tool cluster. At each unit, one or more specific process operations may be carried out. Many different processing units are involved in the fabrication process. Typical units involve cleaning, etching, drying, photolithography, deposition of materials, polishing, planarization, and the like.
Wafer handling (also referred to as wafer transport) refers to techniques by which one or more in-process microelectronic devices are transferred from processing unit to unit (i.e., interstation transfer), or from position to position at a particular unit (intrastation transfer). Wafer handling must be accomplished without damaging or contaminating the in-process microelectronic devices. Wafer handling can be especially challenging when an in-process microelectronic device must be moved after the in-process microelectronic device has been inserted into a chamber that is small or that has been environmentally sealed. For example, consider a representative processing unit at which an in-process microelectronic device is to be treated with one or more treatment gases that are used to dry, clean and/or etch, one or both surfaces of the wafer. Because such treatment gases can be highly corrosive and/or because the treatments must occur under carefully controlled conditions (e.g., controlled temperature, humidity, vacuum, and the like) in which exposure of the wafer to contaminants is to be avoided, the processing chamber of such a unit is desirably environmentally sealed from the ambient.
In many applications, it is desirable to move an in-process microelectronic device upon demand from one position within such a chamber to one or more other positions in the chamber, either before or after the chamber is environmentally sealed. For example, an in-process microelectronic device initially might be loaded by a robot handler or other suitable wafer transport mechanism into the chamber in a loading position, after which the an in-process microelectronic device is then moved by some kind of transport mechanism through a range of motion (perhaps comprising movement along the z-axis, i.e., moved vertically up or down) from the loading position to a processing position in order to more effectively carry out one or more desired treatments. After such treatments are completed, the in-process microelectronic device can be moved to a suitable position (which may be the same as the loading position) from which the in-process microelectronic device may be withdrawn by the robot from the chamber.
If the robot being used to load and withdraw the in-process microelectronic device to and from the chamber is not able to cause the desired movement of the wafer within the chamber for one reason or another, some other type of transport mechanism must be used to accomplish the desired wafer movement. Such a transport mechanism generally may be located inside the chamber, outside the chamber, or it could be positioned at least partially in both locations. It is generally undesirable, however, to incorporate a transport mechanism or a portion thereof into the interior of the chamber itself for a variety of reasons. In particular, the movement and operation of the mechanism can generate contaminating debris as different parts of the mechanism move against each other. This, of course, is to be avoided. Additionally, the corrosive treatment gases used in many treatments can also unduly compromise the useful life of such mechanisms.
Accordingly, it would be much more desirable to position any such transport mechanism outside of the chamber. Yet, exterior placement of the transport mechanism poses significant challenges. Specifically, the mechanical movement created by the actuation mechanism located outside of the chamber must somehow be imparted to the in-process microelectronic device located inside of the chamber without compromising the integrity of the carefully controlled environmental conditions of the chamber. It would be desirable to provide an approach that would allow a wafer to be transported inside of a processing chamber in a manner that avoids generating contaminating debris inside the chamber and that can be used whether the chamber is opened or sealed.